netcat is the only application I can think of that would redirect -h to stderr, and I can't for the life of me fathom why.

I suppose if you're outputting the help information because someone used improper arguments, you might want to redirect it to stderr, but personally even then I wouldn't use stderr because I don't think spamming error logs with fullblown help text is useful - I'd rather just output a single error pointing out the arguments were malformed to stderr. If someone is explicitly calling your application using -h or --help, then you really shouldn't redirect it to stderr.